The present invention relates to a management of space in a peripheral storage group for a data processing system having a data processing device and a plurality of peripheral storages and in particular to a space management method which is preferred for efficient utilization of space in a peripheral storage group by a plurality of users.
A prior art data processing system for allocating space to users for each volume on the basis of a maximum capacity of usage of space and the number of files which can be assigned to each user who is preliminarily registered in a space control table for efficiently using space in the peripheral storage is described in, for example, Japanese Unexamined Patent Publication Sho/60-89258. The term "file" refers to one or a plurality of areas which are physically continuous and in which data can be stored in a volume. In the prior art, the volumes are prevented from being occupied by less users by setting a space usage capacity for each user and by saving excess files to save volumes. However, since the physical total capacity of the volumes is limited, if the total usage capacity of the space used by users exceeds the total capacity of the volumes, migration, that is, data movement between primary and secondary storages will readily occur, resulting in low performance. Accordingly, there are problems that it is necessary to suppress the total usage capacity of space used by users within the total capacity of the volumes and that it is necessary to readjust the usage capacity of space for each user depending upon changes in users which use the volumes. There is also a problem that it is necessary to preset a maximum capacity of a newly added volume to the users if a new volume is added since a maximum usage capacity of space is set in units of a volume.
The above mentioned prior art has a problem that even a file having a very low usage frequency is left in the volume if the usage capacity is within the maximum usage capacity of space although files are saved by maximum usage capacity management of space for each user.